For more than a century, internal combustion engines have been relied upon as a principal source of power in a variety of applications. Of those engines, the most widely used are the reciprocating piston engines which are found in automobiles or other forms of transportation, as well as a variety of industrial and consumer applications. Such engines can be built in a variety of sizes, types and configurations depending on the power requirements of a particular application. Generally, the engine configuration affects the physical size and smoothness of the engine. Common configurations include the straight or inline configuration, the more compact V configuration, and the wider but smoother flat or boxer configuration. Aircraft engines can also adapt a radial configuration which allows more effective cooling. More unusual configurations, such as “H”, “U”, “X” or “W” have also been used with success. Cylinder quantities of these configurations range from a single cylinder up to thirty-two cylinders or more.
Types of reciprocating engines generally include the hot bulb engine, the crude oil engine, the four stroke engine, the six stroke engine, the two stroke engine and the diesel engine. The basic components of a typical reciprocating engine are one or more cylinders, and for each cylinder there is a spark plug (except diesel engines), a piston and a crank. A single sweep of the cylinder by the piston in an upward or downward motion is known as a stroke. The most common engine in use today, the four stroke engine requires two or more complete rotations of the crank shaft to complete the four strokes of the engine. The four strokes refer to intake, compression, power and exhaust strokes that occur during two crank shaft rotations for working cycle of the Otto cycle and diesel engines. The two stroke cycle of an internal combustion engine differs from the more common four stroke cycle by completing the same four processes: intake, compression, power and exhaust in only two strokes of the piston rather than four. This is accomplished by using the beginning of the compression stroke and the end of the power stroke to perform the intake and exhaust functions. This allows a power stroke for every revolution of the crank, instead of every second revolution as in a four stroke engine.
The hot bulb engine shares its basic layout with n early all other internal combustion engines, in that it has a piston inside a cylinder connected to a flywheel via a connecting rod and crankshaft. The flow of gases through the engine is controlled by valves. The majority of hot bulb engines operate on the standard four stroke cycle having an induction stroke, a compression stroke, a power stroke and an exhaust stroke. The main feature of the hot bulb engine is the vaporizer or hot bulb, a chamber usually cast into the engine block and attached to the main cylinder by a narrow opening. Prior to starting the engine from a cold temperature, this vaporizer is heated externally by a blow torch or slow burning wick for as much as a half hour. The engine is then turned over, usually by hand, but sometimes compressed air or an electric motor. As air is drawn into the cylinder through the intake valve, the piston descends for the induction stroke. During the same stroke, fuel is sprayed into the hot bulb through a nozzle by a mechanical jerk pump. Through the action of the sprayer and the heat of the hot bulb, the fuel instantly vaporizes. The air in the cylinder is then forced through the top of the cylinder as the piston rises for the compression stroke, through the opening into the hot bulb where it is compressed, raising the temperature of the air. The vaporized fuel mixes with the compressed air and ignites due to the heat of the compressed air and the heat applied to the hot bulb prior to starting. The resulting pressure drives the piston down for the power stroke. The piston's action is converted to a rotary motion by the crankshaft flywheel assembly, to which equipment can be attached for work to be performed.
The crude oil engine is a type of internal combustion engine that is similar to the hot bulb engine. A crude oil engine can be driven by all sorts of oils such as engine waste oil and vegetable oils. Like hot bulb engines, crude oil engines are mostly used as stationary engines or in boats. They can be run for a very long time, because they are low RPM and are dimensioned for constant running.
Another configuration of the reciprocating engine includes the Bourke engine which has two opposed cylinders with the pistons in a scotch yolk mechanism. The use of the scotch yolk reduces vibration from the motions of the connection rod.
Yet another variation of the reciprocating engine is referred to as the six stroke engine. The six stroke engine captures the waste heat from the four stroke auto cycle and uses it to power an additional power and exhaust stroke of the piston. Designs either use steam or air as a working fluid for the additional power stroke. As well as extracting power, the additional stroke cools the engine and removes the need for a cooling system, making the engine lighter and giving about 40% increased efficiency over the Otto cycle.
Still another variation of the reciprocating engine is called the Twingle engine. The Twingle engine is a two stroke engine, usually of small capacity and gasoline burning. It uses two pistons, one of which controls the inlet ports and the other the exhaust ports. These run in two parallel cylinder bores but share a single combustion chamber, spark plug and cylinder head.
Still yet another alternative version of the reciprocating engine includes the swashplate engine. The swashplate is a type of reciprocating engine that replaces the common crankshaft with a circular plate. Pistons press down on a circular plate in a circular sequence, forcing it to nutate around its center. The key advantage of this design is that the cylinders are arranged in parallel around the edge of the plate and possibly on either side of it as well, and are aligned with the output shaft of the engine rather than at 90 degrees as in crankshaft engines.
Even though the reciprocating engine is available in so many configurations, the design still suffers from numerous disadvantages. One major disadvantage is that the energy released by combustion is converted to work via linearly moving pistons and is then converted to rotational work output when it is transmitted to the crankshaft. This transfer of work output from linear to rotational motion is inherently inefficient for several reasons. For one, the slider crank mechanism that receives the work output from the piston is not at an optimum position for producing high torque on the crankshaft when pressure in the combustion chamber peaks and, consequently, only a portion of the energy generated by the combustion process is transmitted to the crankshaft, with the rest being dissipated in side thrust resulting in frictional work. Additional energy is wasted changing the directional motion of the piston, while the energy directs the piston in a downward motion, the piston must return to the top of the cylinder to complete another cycle.
Numerous alternatives to the reciprocating engine have been proposed. One such alternative is the Wankel rotary engine. In the Wankel engine, the four strokes of a typical Otto cycle occur in the space between a rotor, which is roughly triangular, and the inside of a housing. In the basic single rotor Wankel engine, the oval-like epitrochoid-shaped housing surrounds a three sided rotor bracket similar to a Reuleaux triangle. The central drive shaft, also called an eccentric shaft or E-shaft, passes through the center of the rotor and is supported by bearings. The rotor both rotates around an offset lobe on the E-shaft and makes orbital revolutions around the central shaft. Seals at the corners of the rotors seal against the periphery of the housing, dividing it into three moving combustion chambers. Fixed gears mounted on each side of the housing engage with ring gears attached to the rotor to ensure proper orientation as the rotor moves.
Another alternative engine design is the Sarich orbital engine. The Sarich orbital engine is a type of internal combustion engine, featuring rotary rather than reciprocating motion of its internal parts. It differs from the conceptionally similar Wankel engine by using a shaped rotor that rolls around the interior of the engine, rather than having a trilobular rotor that spins in place. The advantage is that there is no high speed contact area with the engine walls, unlike the Wankel where edge wear is a problem. However, the combustion chambers are divided by blades which do have contact with both the walls and the rotor, and are said to have been difficult to seal due to the perpendicular intersection with the moving impeller.
Yet another alternative internal combustion engine is the trochilic engine. The trochilic engine is composed of two mirror image gull wing segments intermeshed and rotating about a common axis. Varying the relative segment velocities in rotation forms four variable quadrants. The quadrants are functionally a four cylinder engine requiring no mechanically driven valves. Each segment is internally connected to a rotating gear cage that converts the undulating piston motion to a linear rotating output shaft. The segmented piston has a preferred direction of rotation imposed by the mechanically leveraged action of the gear cage.
Another known engine is the toroidal engine design. The toroidal engine design is a form of internal combustion engine that features pistons that rotate within a torodial space. Generally in a toroidal engine, the engine moves pistons on different rotors relative to each other to form combustion chambers of variable volume in a torodial cylinder. The pistons move in a stepwise fashion, and with the pistons on one rotor traveling a predetermined distance while the pistons on the other rotor remain substantially stationary. Fuel is drawn into a chamber as one of the pistons defining a chamber moves away from the other, and then compressed as a second piston moves towards the first. Combustion of the fuel drives the first piston away from the second, and the exhaust gasses are then expelled from the cylinder by the second piston moving again towards the first. An output shaft is connected to the rotors in such a manner that the shaft rotates continuously while the rotors and pistons move in their stepwise fashion. The engine fires as many as 16 times in one revolution of the crankshaft, 32 times on two. By comparision, a standard V8 fires four times per crankshaft revolution, one quarter the number of the torodial engine.
One drawback to the prior art toroidal engines is the requirement that the pistons move in a stepwise fashion. Stopping and restarting the piston movement requires a substantial amount of energy. Therefore, what is needed in the art is an engine with a toroidal shaped power cylinder wherein the pistons move in a continuous motion without the need for the stepwise movement as seen in the prior art. The engine should include one or more charge rings constructed and arranged to supply a fuel air charge to the power ring for combustion.